中文摘要：

针对一种特殊的新型双基合成孔径雷达（SAR）成像模式——弹载双基前视 SAR，由于收发平台较高速度和加速度的引入，距离历程存在双根号下高阶项问题以及该构型相对单/双基直线轨迹 SAR 更为严重的距离徙动问题，提出了一种消除位置空变性的扩展场景成像算法。首先在时域对距离走动量进行校正以减少二维耦合量，然后基于级数反演求得的高精度二维频谱，对各相位项的场景空变性进行量性分析，并通过高阶多项式拟合设计出空变的匹配滤波器，完成扩大场景成像。该方法处理简洁且具有更少的运算量，利于弹载平台下成像分析和后续处理。仿真实验表明，本算法有效校正了场景空变性，提高了场景边缘点的聚焦性能，从而扩大了成像场景范围。

英文摘要：

Due to such problems as high order terms in double square roots and more serious range cell migration than monostatic or bistatic SAR in range history, caused by high velocities and accelerations in both the transmitter and the receiver platforms in a new and special bistatic synthetic aperture radar imaging mode, i. e., missile-borne bistatic forward-looking synthetic aperture radar, an imaging algorithm correcting space variance for the extended scene for is proposed. The range walk is firstly corrected in the time domain to reduce the two dimensional （2D） coupling. And then the space variance of phase terms, in the 2D frequency spectrum of the echo signal with high precision gained by the method of series reversion, is analyzed quantitatively. The imaging is completed through polynomial fitting and variant match filter designing. With simple operation and less computation, our algorithm is convenient for imaging processing and subsequent procedure in the missile-borne platform. Simulation results show our imaging method significantly corrects the space variance, improves the focus quality of fringe targets, and thus extends the imaging scene.